1. Field of the Invention
The subject invention relates to a heat exchanger, and more particularly, to a condenser having a receiver/dehydrator assembly for an air conditioning system for a vehicle.
2. Description of the Prior Art
Modern vehicles are designed to provide passengers with comfort, convenience, and safety. One comfort system that few could live without is an air conditioning system. The air conditioning system used in the modem vehicles is designed to cool, dehumidify, clean, and circulate the air in a vehicle. The air conditioning system presents a closed, pressurized system that has a compressor, a condenser, a receiver/dehydrator (R/D), an expansion valve or orifice tube and a plurality of additional components used in combination therewith to increase efficiency and dependability of the air conditioning system.
The compressor is a heart of the air conditioning system and is designed to separate high-pressure and low-pressure sides of the air conditioning system and includes outlet and inlet portions. The primary purpose of the compressor is to draw the low-pressure and low-temperature vapor from the evaporator and compress this vapor into high-temperature, high-pressure vapor. The secondary purpose of the compressor is to circulate or pump a refrigerant through the air conditioning system under the different pressures required for proper operation of the air conditioning system. The compressor is located in an engine compartment and is driven by the engine's crankshaft via a drive belt.
The condenser includes coiled refrigerant tubing mounted in a series of thin cooling fins to provide maximum heat transfer in a minimum amount of space. The purpose of the condenser is to condense or liquefy the high-pressure, high-temperature vapor coming from the compressor. The condenser is operably connected to the R/D.
The R/D includes first and second tanks or housings. The R/D functions as a storage tank for the liquid refrigerant, wherein the liquid refrigerant flows into the upper tank containing a bag of a moisture-absorbing material such as silica alumina, silica-gel, or the like. The bag is necessary to be present in the upper tank to absorb any moisture present therein that might enter the air conditioning system during assembly and to prevent damage to the compressor.
It is becoming more common for the air conditioning system to use condensers with an integrated R/D. Since the most optimum pressure vessel design is a circular cross section, the upper and lower tanks having circular cross section must be joined to preserve the pressure inside the upper and lower tanks. Many different means have been used to integrate the upper and lower tanks to the R/D of the condenser. The art is replete with various designs of condenser showing integral R/D's. These designs are disclosed in the U.S. Pat. Nos. 5,546,761 to Matsuo et al.; 5,713,217 to Baba; 6,334,333 to Shinhama; 6,470,704 to Shibata et al.; 6,505,481 to Neumann et al., 6,578,371 to Beasley et al.; and the U.S. Patent Application Publication No. 2003/0085026 to Kaspar et al.
Some of the aforementioned patents accomplish the joining through pipe and block or plate style refrigerant connectors. The U.S. Pat. No. 6,578,371 to Beasley et al., for example, teaches a condenser having upper and lower tanks and a mounting bracket operably connected to the lower tank. A pair of pipes are coupled to and extend from the lower tank. The pipes further extend through the mounting bracket to the upper tank and operably connected thereto. The pipes are coupled to the lower tank header of the condenser system prior to furnace brazing, and the upper tank is subsequently mounted to the mounting bracket.
The U.S. Pat. No. 6,334,333 to Shinhama teaches a condenser having an upper tank and a lower tank communicatively connected one with the other by a refrigerant passage of a connection member. The connection member presents a pair of saddles defined therein and having a surface complementary with the circumference of the upper and lower tanks to mimic the dual chamber design. This design requires extra extrusion and braze over large surface area sections, whereby the braze interface is less than ideal.
The most challenging aspect of the integrated design is the refrigerant communication between the condenser and the R/D, preservation of the pressure in the R/D, as well as prevention and elimination of the refrigerant leakage. There is a constant need in the area of an automotive industry for improvements in a condenser having an integrated R/D.